Stepwise Post-glycosylation Modification of Sugar Moieties in Kanamycin Biosynthesis

Chembiochem. 2021 May 4;22(9):1668-1675. doi: 10.1002/cbic.202000839. Epub 2021 Feb 11.

Abstract

Kanamycin A is the major 2-deoxystreptamine (2DOS)-containing aminoglycoside antibiotic produced by Streptomyces kanamyceticus. The 2DOS moiety is linked with 6-amino-6-deoxy-d-glucose (6ADG) at O-4 and 3-amino-3-deoxy-d-glucose at O-6. Because the 6ADG moiety is derived from d-glucosamine (GlcN), deamination at C-2 and introduction of C-6-NH2 are required in the biosynthesis. A dehydrogenase, KanQ, and an aminotransferase, KanB, are presumed to be responsible for the introduction of C-6-NH2 , although the substrates have not been identified. Here, we examined the substrate specificity of KanQ to better understand the biosynthetic pathway. It was found that KanQ oxidized kanamycin C more efficiently than the 3''-deamino derivative. Furthermore, the substrate specificity of an oxygenase, KanJ, that is responsible for deamination at C-2 of the GlcN moiety was examined, and the crystal structure of KanJ was determined. It was found that C-6-NH2 is important for substrate recognition by KanJ. Thus, the modification of the GlcN moiety occurs after pseudo-trisaccharide formation, followed by the introduction of C-6-NH2 by KanQ/KanB and deamination at C-2 by KanJ.

Keywords: aminoglycoside antibiotics; biosynthesis; flavin-dependent dehydrogenases; kanamycin; non-heme iron oxygenases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / metabolism*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Glycosylation
  • Kanamycin / analogs & derivatives
  • Kanamycin / biosynthesis*
  • Kinetics
  • Oxidoreductases / genetics
  • Oxidoreductases / metabolism
  • Polysaccharides / chemistry*
  • Streptomyces / enzymology
  • Substrate Specificity
  • Transaminases / genetics
  • Transaminases / metabolism

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Polysaccharides
  • Kanamycin
  • Oxidoreductases
  • Transaminases

Supplementary concepts

  • Streptomyces kanamyceticus